Magnetodynamic actuator



' May 19, 1970 J. C. W. RANSOM ET AL MAGNE'IODYNAMIC ACTUATOR Filed Dec.20, 1967 United States Patent Int. Cl. H01h US. Cl. 335-164 12 ClaimsABSTRACT OF THE DISCLOSURE A magnetodynamic actuator for operating adevice, such as a vacuum switch, comprises a support upon which a pairof energizable coils are fixedly mounted in spaced apart relationshipalong an axis. A first electrically conductive member (aluminum disk) ismounted on a reciprocably movable shaft and is disposed adjacent onecoil. A second electrically conductive member (copper disk) is movablydisposed adjacent the other coil and is connected to the first disk byresilient means. Impulse energization of the said one coil repulses thealuminum disk away from the first coil and the shaft is moved tooneposition. Impulse energization of the said other coil repulses thecopper disk and causes the resilient means to force the aluminum disktoward said first coil andthe shaft is moved to its other position.Means are provided to latch the shaft in each of its several positions.

SUMMARY OF THE INVENTION This invention relates generally tomagnetodynamic actuators. More particularly, it relates to suchactuators having a movable armature member which is repulsed to one orseveral positions by momentarily energized coil means and which ismaintained in each position by latching means.

Electromagnetic actuators having magnetically permeable armaturesreciprocably movable in response to energization of a pair of spacedapart coils are sometimes employed to operate devices such as switchesor the like. Some actuators of this type employ coils which are requiredto be continuously energized to magnetically attract and maintain thearmature in either or both of its operating positions. Otherelectromagnetic actuators employ coils which respond to impulseenergization to effect reciprocal armature movement by magneticattraction and use a permanent magnet or spring biasing means to retainthe armature in at least one of its operating positions.

I accordance with the present invention there is provided amagnetodynamic (as distinguished from an electromagnet) actuator havinga reciprocably movable armature member which is repulsed to at least oneoperating position by means of impulse energization of an operating coiland which is maintained in its operating position by suitable biasingmeans. The latter type of actuator is powerful and positive inoperation.

OBJECTS OF THE INVENTION I I DESCRIPTION oF THE DRAWING The accompanyingdrawing illustrates a preferred embodiment of the invention but it is tobe understood that the embodiment illustrated is susceptible ofmodifications with respect to details thereof without departing from thescope of the appended claims.

In the drawing, there is shown a cross sectional view of anelectromagnetic actuator in accordance with the present invention and avacuum switch with which it is employed.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawing, there isshown magnetodynamic actuator 10 according to the present inventionwhich is associated with a device which it operates, such as a vacuumswitch 12.

Switch 12 comprises an insulating housing 14 having a cover 16 in whicha vacuum is maintained. A pair of spaced apart contacts 18 and 20 arerigidly mounted within housing 14 and are adapted to be bridged by areciprocably movable bridging contact 22. Bridging contact 22 isconnected to a movable switch operator which comprises a bellows 24which is connected to cover 16 and which is provided with a connector 26for attaching contact 22 to a reciprocably movable shaft 30 of actuator10, hereinafter described. Switch 12 is shown in open condition, i.e.,contacts 18 and 20 are unbridged. It is to be understood, however, thatswitch 12 is closed when contacts 18 and 20 are bridged by downwardmovement of contact 22.

Magnctodynamic actuator 10 has a support or frame 32 comprising a lowermember 34 and an upper member 36 which are secured together by meanssuch as bolts 38 upon which tubular spacers 40 are mounted. Support 32is rigidly connected to switch 12 by having the bolts 38 thread intomounting studs 42 which are connected at 43 to cover 16 of switch 12. Aspring retaining means 46 cylindrical in form is shown associated withupper member 36 of support 32 and, if preferred, could be integraltherewith.

A first repulsion coil 50 in the form of a flat pancake winding with acentral opening 51 is rigidly secured to the lower face of upper member36 of support 32, as by an adhesive.

A second repulsion coil 52, similar to coil 50 and having a centralopening 53, is similarly secured to the upper face of lower member 34 ofsupport 32.

The coils 50 and 52 are adapted to be selectively and individuallyenergized by momentary DC electrical current pulses by a suitablecontrol means 55 to effect reciprocal movement of a movable means ofactuator 10 which, in turn, moves the operator of switch 12, as willhereinafter be described. The movable means of actuator 10 comprises alower portion 84 and an upper portion 90.

Energization of coils 50 and 52, as hereinafter explained, effectsreciprocal movement of the movable means which is located between thecoils. The movable means comprises an electrically conductive member 86which is mounted on shaft 30 and further comprises another electricallyconductive member 92 which rests on a resilient means or spring 96 onmember 86. Conductive members 86 and 92 are understood to be made ofmaterials having high electrical conductivity and are adapted to havehigh currents induced therein when the coils 52 and 50, respectively,are energized. In the embodiment shown, the movable means preferably hasa relatively low mass so that it can be rapidly accelerated in eitherdirection. Accordingly, conductive member 86 is an aluminum disk andother movable components are made of lightweight materials. However,conductive member 92 is a copper disk which weighs substantially morethan disk 86 so that the energy transferred to disk 86 by disk 92, ashereinafter explained, is sufficient to drive the movable means downward(with respect to the drawing) with high momentum and afterward continuesto press upon disk 86 to reduce contact bounce.

Shaft 30 of the movable means of actuator is reciprocably movable alongits axis and is connected to movable contact 22 of switch 12. Shaft issupported and aligned by a sleeve 70 on lower member 34 of support 32and by an opening 72 in sleeve 46. Disk 86 is mounted on shaft 30 insuch a way as to effect reciprocal movement of the shaft but isresiliently connected in such a manner as to allow for limited relativemovement and overtravel. Thus, disk 86 is movable between a flange atone end of a sleeve 82 on shaft 30 and a washer 78 at the other end heldby a nut 80. Disk 86 is biased against washer 78 by a spring 88surrounding sleeve 82. As hereinafter, explained, repulsion between disk86 and coil 52 effects upward movement of shaft 30 to switch openposition.

Disk 92 rests on a resilient means such as a compression spring 96 whichin turn rests upon disk 86. As hereinafter explained, repulsion betweendisk 92 and coil 50 effects downward movement of disk 92, compression ofspring 96, downward movement of disk 86, and downward movement of shaft30 to switch closed position. Because disk 92 is relatively heavy, ithas high momentum when moving and exerts a high inertial force on disk86. Shock absorber means in the form of a sponge rubber ring 94 islocated between the disks 86 and 92 and is preferably attached to thelatter.

Latching means are provided for maintaining the movable means in theseveral positions into which it is moved. Thus, spring biasing means areprovided to maintain shaft 30 in its upward or switch open position andsuch means take the form of a compression spring 76 located in springretaining means 46 and a resilient strap 74 connected between shaft 30and support 32. Permanent magnet means are provided to maintain shaft 30in its downward or switch closed position and such means take the formof a permanent magnet assembly 54 mounted on lower member 34 of support32 and a magnetically permeably pole piece 68 mounted on disk 86.Permanent magnet assembly 54 is located concentrically of coil 52 andcomprises a magnetically permeable cup 56 in which an Alnico magnet 58is secured as by an adhesive 62. Cup 56 is secured -by bolts 64 and hasa rubber disk shock absorber 66 located therebeneath. Permanent magnetassembly 54 is adapted to shape the permanent magnet field in such a wayas to concentrate the flux in pole piece 68 for improved latching.

Actuator 10 and vacuum switch 12 associated therewith operate asfollows, assuming that both are initially in the open or first positionshown in the drawing. In this position the movable means is latched in aposition wherein disk 92 is adjacent coil 50. To move the movable meansto closed or second position, upper coil 50 is momentarily energized bya pulse of DC. current. This causes an oppositely flowing electriccurrent to be induced in copper disk 92 and similar magnetic fields arethereby established between coil 50 and disk 92 causing repulsion. Disk92 moves away from coil 50 and causes spring 96 to be compressed againstaluminum disk 86 to force the latter to overcome the bias of spring 88.Iron pole piece 68 then makes contact with pole piece 60 of permanentmagnet assembly 54. Continued downward motion (overtravel) of heavy disk92 maintains pole piece 68 in position with respect to permanent magnetassembly 54 for a length of time sufficient for magnetic flux linkagesto build up and latch it in closed position. Compression of spring 88 bydownward movement of pole piece 68 and disk 86 causes a force to beexerted on sleeve 82 and shaft 30 is thereby moved downward to closedposition wherein it causes contact 22 of switch 12 to bridge contacts 18and 20. Upward rebound of disk 92 and its related components is of noconsequence and does not effect latch release. When the movable means islatched in closed or second position, spring 88 is slightly compressedand consequently exerts a downward force on sleeve 82, shaft 30 andbridging contact 22 to force the latter against contacts 18 and 20. Tomove the movable means back to its first or open position, shown in thedrawing, lower coil 52 is momentarily energized by a pulse of DCcurrent. This causes an oppositely flowing electric current to beinduced in aluminum disk 86 and like magnetic fields are therebyestablished between coil 52 and disk 86. Disk 86 moves away from coil 52and causes spring 96 to be compressed against copper disk 92. Upwardmovement of disk 86 also exerts a force against abutment 78 on shaft 30thereby causing the shaft to move upwardly and open contact 22. Theupward movement of shaft 30 is aided by the upward biasing action ofspring 76. Spring 76 supplies sufiicient force to overcompensate for allassociated gravitational forces and to hold shaft 30 in open position.As disk 86 continues its upward movement it hits resilient component '94on disk 92 and causes disk 92 to hit and come to rest against upper coil50. Disk 86 then bounces oif component 94 and upward movement of disk 86is checked.

In the embodiment of the invention disclosed herein, magnetodynamicactuator 10 comprises two repulsion coils and two electricallyconductive members or disks 86 and 92. It is to be understood, however,that a greater or lesser number of coils and disks could be employed inaccordance with the invention. Similarly, whereas the electricallyconductive members are shown as solid metallic disks, it is apparentthat these members could have some other form, for example, such as amember made of insulating material having a thin coating or plating ofelectrically conductive material such as gold. Finally, it will beapparent that other forms and arrangements of latching means might beprovided.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows: 1. In a magnetodynamicactuator for operating a device having movable operator,

a support, at least one repulsion coil on said support adapted to bemomentarily energized by an electrical pulse,

movable means relatively movable with respect to said support andadapted to effect movement of said movable operator of said device, saidmovable means comprising at least one electrically conductive memberwherein electric currents are induced to generate a magnetic field oflike field to that generated by said one repulsion coil, said conductivemember having a first position adjacent said one repulsion coil andhaving at least a second position whereto it is repulsed in response tomomentary energization of the latter,

and latching means on said support and on said movable means formaintaining the latter in its several positions.

2. An actuator according to claim 1 wherein said latching meanscomprises permanent magnet means for maintaining said movable means inat least one of its several positions and further comprises biasingmeans for maintaining said movable means in at least another of itsseveral positions.

3. An actuator according to claim 2 wherein said permanent magnet meansmaintains said movable means in said first position and said biasingmeans maintains said movable means in its said other position.

4. In a magnetodynamic actuator for operating a device having a movableoperator,

a support,

first and second spaced apart repulsion coils on said support,

each coil adapted to be momentarily energized by an' electric pulse,movable means relatively movable with respect to said support andadapted to efiect movement of said movable operator of said device,

said movable means comprising first and second electrically conductivemembers,

each electrically conductive member adapted to have electric currentsinduced therein to generate a magnetic field of like field to thatgenerated by the repulsion coil associated therewith,

said movable means having a first position wherein said firstelectrically conductive member is adjacent said first repulsion coil andhaving a second position wherein said second electrically conductivemember is adjacent said second repulsion coil,

said movable means being movable to either of its positions in responseto repulsion of that electrically conductive member adjacent itsrespective coil when the latter is momentarily energized,

and latching means on said support and on said movable means formaintaining the latter in each of its several positions.

5. An actuator according to claim 4 wherein said first and secondelectrically conductive members are movable with respect to each otherand wherein said movable means further comprises resilient meansassociated with both electrically conductive members whereby each ofsaid electrically conductive members when repulsed by its respectiverepulsion coil drives the other electrically conductive member to thelatters position adjacent its respective repulsion coil.

6. An actuator according to claim 5 wherein said latching meanscomprises biasing means which biases one of said electrically conductivemembers into a position away from its respective repulsion coil andsimultaneously causes said resilient means to bias the other of saidelectrically conductive members into its position adjacent itsrespective repulsion coil.

7. An actuator according to claim 6 wherein said latching means furthercomprises permanent magnet means for biasing the said one of saidelectrically conductive members into a position adjacent its respectiverepulsion coil.

8. An actuator according to claim 7 including shock absorber meansmounted between said electrically conductive members.

9. In a magnetodynamic actuator for operating a device having a movableoperator,

a support,

first and second spaced apart repulsion coils on said support,

each coil adapted to be momentarily energized by an electric pulse,

a shaft mounted on said support and movable from a first position to asecond position to effect operation of said movable operator of saiddevice,

one electrically conductive member mounted on said shaft to effectmovement of the shaft to first position when said second coil ismomentarily energized,

biasing means connected between said support and said shaft to latch thelatter in said first position,

permanent magnet means supported by said support and said shaft to latchthe latter in said second position,

another electrically conductive member disposed between said first coiland said first electrically conductive member,

and a resilient means disposed between both of said electricallyconductive members upon which said other electrically conductive memberrests to effect movement of said shaft to second position when saidfirst coil is momentarily energized.

10. An actuator according to claim 9 wherein said other electricallyconductive member has substantially higher mass than said oneelectrically conductive member so that the energy transferred to saidother member by said first coil is sufiicient to drive said shaft to itssecond position.

11. An actuator according to claim 10 wherein said one electricallyconductive member is resiliently connected to said shaft to allow forlimited relative movement therebetween.

12. An actuator according to claim 11 wherein shock absorber means aremounted between both of said electrically conductive members.

References Cited UNITED STATES PATENTS 3,070,730 12/1962 Gray 3352563,109,906 11/ 1963 Abendroth 335 3,202,886 8/1965 Kramer 335-2543,223,802 12/1965 Horst 335-267 3,275,964 9/1966 Kumm 335-267 BERNARD A.GILHEANY, Primary Examiner H. BROOME, Assistant Examiner US. Cl. X.R.335-266

